A significant lunar event will be unfolding on January 31, bringing about a stunning show in the sky while causing havoc with tides and coastal flooding. The January 31st full moon is the second full moon of the month, with the first arriving on January first. Because more than one full moon in the same month is rare, it’s commonly known as a “Blue Moon.” This Blue Moon will also be eclipsed by the Earth’s shadow; in areas of total eclipse, the moon will appear reddish brown. Because of that, this unique phenomena is known as a “Blood Moon.” And as if this full moon wasn’t special enough, it is also a Supermoon, the third of a trilogy that brought supermoons to December 3, January 1, and now January 31. A supermoon is a Moon that is full when it is also at or near its closest point in its orbit around Earth.
Viewing the Supermoon or a total or partial eclipse are completely safe; you do not need to wear any special glasses. Because the moon is lit by the sun, looking at the moon is no more harmful than looking at a tree lit by sunlight.
Beyond the stunning show in the sky, the full moon will lead to very high tides that could cause coastal flooding concerns. The proximity of the Moon in relation to Earth and Earth in relation to the Sun has an effect on tidal ranges. The Moon moves around Earth in an elliptic orbit that takes about 29 days to complete. The gravitational force is greatest when the Moon is at perigee. The king tides occur when the Earth, Moon and Sun are aligned at perigee and perihelion, resulting in the largest tidal range seen over the course of a year. These unusually significant coastal tides have been nicknamed “King Tides” and could create problems in coastal communities prone to coastal flooding. Any coastal storm that arrives with a King Tide makes things worse, adding to coastal flood and beach erosion threats.
“The supermoons are a great opportunity for people to start looking at the Moon, not just that once but every chance they have!” says Noah Petro, a research scientist from NASA’s Goddard Space Flight Center.
“The lunar eclipse on January 31 will be visible during moonset. Folks in the Eastern United States, where the eclipse will be partial, will have to get up in the morning to see it,” notes Petro. “But it’s another great chance to watch the Moon.” The eclipse will be total in Hawaii, giving residents and visitors there a full Blood Moon experience. Depending on weather and location, spotting the lunar action may be best either in the morning of the 31st or the night.
Apogee and Perigee
The moon’s orbit around Earth is far from a perfect circle. The 27 day voyage of Earth’s satellite is actually an elliptical orbit with an ever changing distance. The casual observer will notice the phases of the moon as it makes this orbit but the more subtle change, and also noticeable, is the slight change in distance as well. During the course of any given month the distance between the Earth and the moon will vary by close to 30,000 miles. The farthest point is called apogee, the moon being a distant 252,712 miles from Earth. Perigee is the closest point with that distance shrinking to 221,519 miles. A full moon at perigee will appear a bit larger and much brighter than a full moon at apogee.
The Supermoons in this Trilogy won’t be nearly as spectacular as the November 2017 Supermoon. The November 14, 2017 full moon occurred within 2 hours of the point when the moon was at perigee. Before 2016, this happened last in January of 1948 and will not happen again until November of 2034.
The supermoon classification is a term that was coined by astrologer Richard Nolle in 1979. Nolle used the supermoon term to describe a new or full moon that occurs when the moon is in the top 10% of it’s closest distance to Earth. There was never a reason given why the 10% value was chosen and the term “supermoon” is not recognized in the astronomical community, but has certainly taken hold with the general population and media reports. Given that every 27 days there is a full and new moon along with perigee and apogee point the supermoon is not that uncommon.
The best time to really appreciate the supermoon will be as the moon is close the the horizon and will appear larger due to the moon illusion phenomenon.
See how one photographer captures the moon in stunning pictures around New York City here: Photographer Wows with NYC Imagery